The present invention relates to vehicle seats fitted with pivot mechanisms.
More specifically, the invention relates to a vehicle seat having first and second frames, mounted so as to pivot relative to one another about an axis of rotation by means of at least one pivot mechanism, designed to allow a user to choose and lock a relative angular position of the first and second frames, this pivot mechanism comprising first and second rigid side plates fixed respectively to the first and second frames of the seat, at least the first side plate having an external relief design (projecting or indented) arranged in an annular zone essentially centred on the axis of rotation and which co-operates by meshing with a matching relief design of the first frame in order to lock this first side plate and this first frame relative to one another in rotation.
Document EP-A-0 505 229 describes an example of such a seat, as does document EP-A-0 502 774. In the known seats of this type, the first side plate is permanently joined to the first frame by several screws, generally three, so that mounting the pivot mechanism on the seat frames is a lengthy and costly operation. Furthermore, these screws provide anchoring at certain points only, which does not prevent the frame from becoming deformed and in particular from buckling when subjected to a high pivot torque (in the event of an accident, for example), which limits the mechanical strength of the seat.
The specific objective of this invention is to overcome these drawbacks.
To this end, the invention proposes a seat of the type in question, wherein the first side plate is permanently fixed by a single, threaded fixing member which extends substantially along the axis of rotation and co-operates with a complementary threaded fixing member by a screwing action, applying a flange against the first frame in the direction of the first side plate, at least on an annular bearing zone adjacent to a relief design of the first side plate and a matching relief design of the first frame.
As a result of these features, the pivot mechanism is easier to mount on the seat frames and the mounting is stronger.
In preferred embodiments of the invention, one and/or the other of the following features may be incorporated:
the relief arrangement of the first side plate is provided as a toothed ring, centred on the axis of rotation and having radially oriented teeth, the complementary relief arrangement also being provided in the form of a ring of teeth;
the flange is integral with the complementary threaded fixing member and bears on a smooth and flat part belonging to the first frame;
the flange is a separate part from the complementary threaded fixing member;
the flange is immobilised in rotation due to a meshing action with the relief design of the first side plate;
the complementary threaded fixing member has a head which bears on a washer which in turn bears on the flange;
the complementary threaded fixing member is a screw;
the complementary threaded fixing member is a nut which is screwed from the outside onto a threaded end constituting said threaded fixing member;
the first and second frames belong respectively to a seat part and a backrest forming the seat.